This invention pertains to engine controls and more particularly a novel electronic circuit for such a system. In the preferred embodiment the invention pertains to an improvement in an engine spark timing control system. The copending U.S. application Ser. No. 570,671 discloses and claims a novel engine control system, one novel feature of which relates to the development of a programmed vacuum advance signal for controlling engine spark timing.
The present invention is directed toward a novel engine electronic control circuit which may be used, inter alia, for developing a programmed vacuum advance signal. With the present invention there is provided a reliable, versatile, efficient and economical circuit arrangement which: develops a signal representative of the instantaneous value of an engine operating parameter (for example, engine manifold vacuum); develops an accumulation function representative of engine operation in selected operating modes (for example, in engine idle and non-idle conditions); and modulates the accumulation function and the operating parameter signal together to develop a programmed output signal (for example, a programmed vacuum advance signal).
Further features and advantages of the invention will be seen as the description proceeds.